FIG. 1 is a conceptual view showing an example of a fundamental optical arrangement of a conventional microscope of this type. Also, for convenience of comparison with the present invention to be described later, the figure is upside down.
The microscope shown in FIG. 1 has an objective lens 51, an imaging lens 52, an image sensor 53, an illumination light source 54, and a reflecting fluorescence illumination optical system 56. Also, in FIG. 1, reference symbol P denotes the pupil position of the objective lens 51 and O denotes the center axis of the objective lens 51 and the imaging lens 52. The imaging lens 52 is designed to project light passing through the objective lens 51 and to form the image of a specimen 57.
The image sensor 53 is located at the position where the image of the specimen 57 is formed by the imaging lens 52. The reflecting fluorescence illumination optical system 56 is constructed to have a dichroic mirror 55 introducing light from the illumination light source 54 into an optical path on the objective-lens-51 side and to illuminate the specimen 57 with the light.
In the microscope shown in FIG. 1, a desired optical member is inserted in the optical path between the objective lens 51 and the imaging lend 52 in accordance with an observation application. In the example of FIG. 1, an arrangement for a fluorescence observation is shown, and an excitation filter 58 and a barrier filter 59 are arranged on the illumination-light-source-54 side of the dichroic mirror 55 and on the specimen-57 side, respectively.
In the microscope shown in FIG. 1, light emitted from the illumination light source 54 is incident on the reflecting fluorescence illumination optical system 56, and light with excitation wavelength alone is extracted through the excitation filter 58 in the reflecting fluorescence illumination optical system 56 and is incident on the dichroic mirror 55. The light is reflected by the dichroic mirror 55 and enters the objective lens 51 to irradiate the specimen 57 through the objective lens 51. Light from the specimen 57, containing fluorescent light, passes through the objective lens 51 and is transmitted through the dichroic mirror 55 to enter the barrier filter 59. Light in which unwanted wavelength other than desired fluorescent light is cut off through the barrier filter 59 is incident on the imaging lens 52 and is formed as the image of the specimen 57 on the image pickup surface of the image sensor 53 through the imaging lens 52 so that the image is picked up by the image sensor 53. The image of the specimen 57 picked up by the image sensor 53 can be observed as a picture through a display device omitted from the figure. A conventional microscope of such a type is set forth, for example, in Japanese Patent Kokai No. 2000-98244.